With regard to such a kind of control unit, it has been proposed to perform a model predictive control. For example, according to a model predictive control described in JP2008-228419A, an electric current flowing in a three-phase electric motor is predicted with regard to each of variously set operation states of an inverter, and the inverter is controlled to an operation state where deviation between a predicted electric current and a command current is minimum. Namely, the inverter is controlled to optimize the behavior of electric current predicted based on the operation state of the inverter. Therefore, followability to the command current in a transient time improves. It is considered that such a model predictive control is effectively used in a device requiring high performance as transient followability, such as in a control unit of a motor generator as an in-vehicle main device.